The ancient geographers divided Arabia into three parts,—_Arabia Petræa_, or the Rocky, comprising the northwestern portion, including the Sinaitic peninsula, between the Gulfs of Suez and Akaba; _Arabia Deserta_, the great central desert; and _Arabia Felix_, the Happy, by which they appear to have designated the southwestern part, now known as Yemen. The modern Arabic geography, which has been partly adopted on our maps, is based, to some extent, on the political divisions of the country. The coast region along the Red Sea, down to a point nearly half way between Djidda and the Straits of Bab-el-Mandeb, and including the holy cities of Medina and Mecca, is called the Hedjaz. Yemen, the capital of which is Sana, and the chief sea-ports Mocha, Hodeida, and Loheia, embraces all the southwestern portion of the peninsula. The southern coast, although divided into various little chiefdoms, is known under the general name of Hadramaut. The kingdom of Oman has extended itself along the eastern shore, nearly to the head of the Persian Gulf. The northern oases, the seat of the powerful sect of the Wahabees, are called Nedjed; and the unknown southern interior, which is believed to be almost wholly desert, inhabited only by a few wandering Bedouins, is known as the Dahna or Akhaf. Arabia has been inhabited by the same race since the earliest times, and has changed less, in the course of thousands of years, than any other country of the globe, not excepting China. According to Biblical genealogy, the natives are descended from Ham, through Cush; but the Bedouins have always claimed that they are the posterity of Ishmael. Some portions of the country, such as Edom, or Idumæa, Teman and Sheba, (the modern Yemen,) are mentioned in the Old Testament; but neither the Babylonian, Assyrian, Persian, nor Egyptian monarchies succeeded in gaining possession of the peninsula. Alexander the Great made preparations for a journey of conquest, which was prevented by his death, and Trajan was the only Roman emperor who penetrated into the interior.